MXPA99004658A - Combined mixtures of formamidinsulfin acid - Google Patents

Abstract

The present invention relates to mixtures consisting of formamidinsulfinic acid, an anti-deposition agent in particular neutral or acid and / or silicic acid in the form of fine particles, with good drainability to be used in reducing bleaching in the paper and textile industry, especially polycarboxylates being applied. polyacrylic acids with a content of about 10% of a polyamide, in the form of a copolymerized

Description

COMBINED MIXTURES OF FORMAMIDINSULFINIC ACID Field of the Invention The present invention relates to combined mixtures containing formamidinsulfinic acid (FAS), at least one agent to prevent deposition and / or silicic acid in the form of fine particles.

BACKGROUND OF THE INVENTION Formamidinsulfinic acid (FAS) is used in reducing bleach in the paper and textile industry, in the form of an alkaline aqueous solution. Although FAS is relatively insoluble in water (approximately 27 g / 1), under alkaline conditions, up to 100 g / 1 of FAS are dissolved in the form of sulfinate. For the bleaching liquor the optimum ratio of the amounts of FAS and bleach (NaOH, Na2CO3) is about 2 to 1. The disadvantage is that the salts of the formamidinsulfinic acid decompose rapidly in the aqueous solution. Therefore bleaching solutions are prepared shortly before dosing and then have to be consumed without loss of time. REF .: 30381 Description of the Invention For the preparation and continuous dosing of FAS and NaOH bleaching solutions, a special dosing facility has been designed which is in service in the facilities of the majority of FAS customers. These facilities operate 24 hours a day (depending on need, seasons or for several months). The labor necessary for the permanent supervision of the dosing of the FAS is not available, or is scarce. Although the addition of the FAS alkaline bleaching solution works well in the case of the continuously operating dosing facility, it is the case that dosing the FAS always leads to new operational problems, the FAS clusters in the funnel or loading or introduction chimney, and does not drain, which has as a consequence a diminished addition as well as a densification of the FAS in the area of the conveyor screw. To solve this problem, the incorporation of vibrators or pneumatic taps in the loading chimney is currently used. Due to the variability of the capacity of draining / aptitude of the grams, it is frequent that the dosed quantities vary, even keeping the rpm of the conveyor screw constant.

The storage of the FAS also presents difficulties very frequently, since the FAS only enjoys a reduced thermal stability. Thus, the SADT (self accelerating decomposition temperature = temperature of the auto-accelerating decomposition) of approximately 50 ° C, given that depending on the temperature conditions, temperatures greater than 30 ° C must be taken into account every time, there are problems related to stability during storage. Already after a few months there is a clear reduction of the runoff capacity until the agglutination (The FAS is not very hygroscopic), a yellow color appears and the content of the thiourea rises. The latter is especially important, when in many countries the mandatory characteristic limit of thiourea (TH, Thioharnstoff) must not exceed 0.1%. Although many of the usual phlegmatizing agents in the industry improve the thermal stability of the FAS, it is not possible to incorporate them in the mixture, since they are the cause of an unpleasant odor, similar to that of hydrogen sulfide. In addition to bad runoff, scale incrustations, especially in dissolution vessels and conductive dosing pipes of FAS, represent a problem. Due to the high pH value of the FAS bleaching solutions, the usual lamellar inhibitors generally show a limited effect. To combat scale incrustations it is necessary to stop the installations, 'rinse them with mineral acids,' and clean them The purpose of the invention is to prepare an FAS that retains its drainability even under storage conditions and which, when used, prevents formation of lime scale Another purpose of the present invention is to increase the stability under storage conditions, by phlegmatizing the FAS. One of the objects of the present invention consists of combined mixtures consisting of FAS, an anti-deposition agent (in the form of powder or granules) of a preferably acidic or neutral pH, and / or a hydrophilic silicic acid in the form of fine particles, preferably precipitate. However, it is also possible to use hydrophobic silicas. Phlegmatization of the FAS is already present when the silicic acid has been newly incorporated, alone, into the mixture. If the combined mixture contains the anti-deposition agent and silicic acid, it is preferable that the FAS be added to "a mixture prepared in advance consisting of anti-deposition agent and silicic acid in the desired concentration ratios. it is added in an amount of 0.001% by weight to 5% by weight, in particular from 0.01% by weight to 2% by weight, based on the total amount of the combined mixture.Therefore, the applied silicic acids have a BET surface (N2) (DIN 66131) of 60 to 700 m2 / g, in particular of 100 to 450 m2 / g.As anti-deposition agents, complex water-soluble complexing agents, such as polymers, are used. (carboxylates), polyphosphonic acids, citric acids, but in particular polyacrylic acids obtained by hydrolysis, and their alkali metal salts, especially sodium salts, such as the copolymers of maleic acid / acrylic acid and their sodium salts, or mixtures thereof They are applied in an amount of 0.05 to 4% by weight, preferably 0.1 to 2% by weight, based on the total amount of the combined mixture, in the same, in solid form. Another object of the present invention is the use of polyacrylic acids, in which about 10% polyamide is contained as a copolymer. Among the polycarboxylates applied are those of the general structure (X, Y), in which X represents A - (CH- C) m- B COOM and Y represents - (F) q_, with the following meanings: A = H, OH, alkyl of 1 to 6 carbon atoms, CH 2 CO (DECO) r_? OM, B = H, OH, alkyl of 1 to 6 carbon atoms carbon, COOM; D = 0, NH; F = a copolymerizable monomer; M = H, alkali metal or alkaline earth metal, ammonium, substituted ammonium; for X also - (CH2-CH2-0) 2_4M; r = 1-5; m = 0.5 to 100% mol; q = 0-99.5 mol%, Said compounds have been disclosed in DE-S 4303320 together with the use of the co-builder in coatenants. The polycarboxylates can be used both in the form of acids as well as salts or as partially neutralizing substances; Counter-ions are also suitable metal ions as nitrogen-containing cations. The polymers applied according to the invention of the structures (X, Y) are preferably homo- or copolymers of acrylic acids. The distribution of the monomers in the polymer is usually statistical (random). It is advantageous if the copolymerizable F monomer is chosen such that it does not influence the anti-deposition effect of the polymer as a whole. Suitable monomers F include monomers free of carboxyl, monoethylenically unsaturated groups, such as, for example, hydroxy (meth) acrylates with (CH 2) X 0 H as ester groups, where x = 2 to 4 (Met) acrylamide, (met) acrylonitrile, vinyl sulfonic acids, alkylsulfonic acids, dimethylaminoethyl (meth) acrylate, diethyl aminoethyl (meth) acrylate, 2- (meth) acrylamido-2-methylpropanesulfonic acid, vinylphosphonic acid, allyl phosphonic acid, hicholyl alcohol, vinyl glycol, acetate of vinyl, allyl acetate, N-vinylpyrrolidone, N-vinylformamide, N-vinylimidazole, N-vinyl midazilidine, 1-vinyl-, -2-methyl-2-imidazoline, ester of (meth) acrylic acids with 1 to 8 carbon atoms in the alcohol radical, such as for example methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate; butyl (meth) acrylate optionally functionalized with alcohol or amino groups; ethylene, propylene, methyl vinyl ether, ethyl vinyl ether, styrene and methylistirol. All monomeric acids and bases can eventually also be used as salts. Ethylene glycol, propylene glycol, butanediol or hexandiol with (meth) acryl-, malein-, or fumaric acid, polyethylene glycol ester or ethylene- and propylene glycol copolymers are among the ethylene-ethylene glycol monomers that are several times unsaturated. (meth) acrylic acids, maleinic, or fumaric acids, accumulation products esterified two to three times with (meth) acrylic or maleic acid, ethylene oxide and / or propylene oxide in trimethylolpropane, at least double acid ester (meth) acrylic- and maleic and glycerin or pentaerythritol, triallyl amine, tetraalliethylene, diamine, polyethylene glycol divilin ether, trimethylol propandialyl ether, butan dioldiallyl ether, pentaerythrityltriallyl ether, divinyl urea.

Suitable for the component X are monoethylenically unsaturated mono or dicarboxylic acids of 3 to 8 carbon atoms, such as, for example, acrylic acids, methacrylic acids, fumaric acids, maleic acid as well as maleic anhydride, itaconic acid, cyclic acid. Also suitable are esters and amides derived from these compounds. Also suitable are polymers derived from these compounds, which are juxtaposed from various building blocks of the structural element X. The difference between the one or more anti-deposition agent (s), present individually or jointly, and the silicic acid, It is filled with the usual FAS in commerce, until reaching 100% by weight. It is also possible to add nitrogen-containing carboxylic acids, such as for example EDTA or DTPA. In this case, given the prevailing pH values in the bleaching liquor, it should be calculated with reduced effectiveness. The combined mixtures are prepared in a known manner and can be dissolved very well under the conditions of practice. The effect of the bleaching is not modified with respect to the FAS that does not contain the additional mixtures according to the invention.

Tests with combined FAS mixtures, containing 0.3% by weight of a commercially spray-dried mixture of silica, lead to a product that also remains "drainable" after several months and It also presents the desired stability under storage conditions Under the determining operating conditions for the evaluation, no depositions were formed in the dissolution vessel or in the pipes.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Having described the invention as above, property is claimed as contained in the following:

Claims (11)

RE I V I ND I CA C I ONE S

1. Combined mixtures consisting of formamidyl sulfinic acid (FAS), characterized in that at least one anti-deposition agent and / or silicic acid in the form of fine particles.

Combined mixtures according to claim 1, characterized in that they contain from 0.05 to 4% by weight of the anti-deposition agent (s) and / or from 0.001 to 5% by weight of the silicic acid, based on in each case, to the total amount of the combined mixture.

Combined mixture according to claim 1, characterized in that the anti-deposition agent (s) has an acid or neutral value for the pH.

Combined mixtures according to one or more of the preceding claims, characterized in that the anti-deposition agent (s) is, individually or in the form of a mixture, a poly (carboxylate), a polyphosphonic acid or citronic acid or its soluble salt, especially its alkaline salt

5. Combined mixtures according to claims 1 to 3, characterized in that the anti-deposition agent (s) is (are) a polyacrylic acid or its sodium salt.

6. Combined mixtures according to claims 1 to 3, characterized in that the anti-deposition agent (s) is (are) a copolymerized maleic acid / acrylic acid or its sodium salt

7. Combined mixtures according to claim 5, characterized in that the polyacrylic acid contains about 10% of a polyamide in the form of a copolymer

8. Combined blends according to claim 4, characterized in that the anti-deposition agent (s) corresponds to a polycarboxylate of the general structure ( X, Y), in which X represents A - (CH- C), B COOM and Y represents - (F) q_, with the following meanings: A = H, OH, alkyl of 1 to 6 carbon atoms, - CH 2 CO (DECO) r-? OM, B = H, OH, alkyl of 1 to 6 carbon atoms, COOM; D = O, NH; F = a copolymerizable monomer; M = H, alkali metal or alkaline earth metal, ammonium, substituted ammonium; for X also - (CH2-CH2-0) 2-4M; r = 1-5; -and m = 0.5 to 100% mol; q = 0 - 99.5% mol.

9. Combined mixtures according to claim 7, characterized in that the anti-deposition agent corresponds to a polycarboxylate, composed of structural blocks of the structural element X.

Mixed mixtures according to one or more of the preceding claims, characterized in that the silicic acid is a precipitated silicic acid, preferably spray-dried, with a specific surface area of 60 to 700 m2 / g (BET, N2).

11. Use of the combined blends according to one or more of the preceding claims, for reducing bleach.